Control of data transmission based on HARQ in a wireless communication system

ABSTRACT

Techniques for controlling data transmission in a wireless communication system based on hybrid automatic retransmission (HARQ) are described. In one design, a user equipment (UE) may determine the number of HARQ processes (Z) supported by the UE, e.g., based on the amount of resources available at the UE. The UE may send information indicative of the number of HARQ processes supported by the UE to a Node B. The UE may thereafter receive data from the Node B on up to Z HARQ processes. In one design, the UE may receive data for non-guaranteed bit rate (non-GBR) traffic on up to Z HARQ processes and may receive data for guaranteed bit rate (GBR) traffic on up to all HARQ processes available in the system. In another design, the UE may receive data for both GBR traffic and non-GBR traffic on up to Z HARQ processes.

The present application claims priority to provisional U.S. ApplicationSer. No. 61/028,159, entitled “METHODS AND APPARATUSES FOR DOWNLINK FLOWCONTROL,” filed Feb. 12, 2008, assigned to the assignee hereof andincorporated herein by reference.

BACKGROUND

I. Field

The present disclosure relates generally to communication, and morespecifically to techniques for controlling data transmission in awireless communication system.

II. Background

Wireless communication systems are widely deployed to provide variouscommunication content such as voice, video, packet data, messaging,broadcast, etc. These wireless systems may be multiple-access systemscapable of supporting multiple users by sharing the available systemresources. Examples of such multiple-access systems include CodeDivision Multiple Access (CDMA) systems, Time Division Multiple Access(TDMA) systems, Frequency Division Multiple Access (FDMA) systems,Orthogonal FDMA (OFDMA) systems, and Single-Carrier FDMA (SC-FDMA)systems.

A wireless communication system may include a number of Node Bs that cansupport communication for a number of user equipments (UEs). A UE maysupport various applications (e.g., voice, video, email, text messaging,etc.) that may run concurrently. Each application may require a certainamount of resources at the UE, e.g., processing resources, buffers,battery power, etc. The amount of resources required by all activeapplications may change dynamically.

The UE may be designed to handle the worst-case load condition and maybe dimensioned with the sum of the resource requirements of allapplications installed at the UE. The worst-case load condition mayoccur when all of the applications are active at the same time and theUE is receiving data at peak rates for all applications currently.However, designing the UE for the worst-case load condition may greatlyincrease the cost of the UE and may not be justified since thissituation may rarely occur, if at all.

In order to keep cost at a reasonable level, the UE may be designed tohandle common load conditions, which may require significantly lessresources than the worst-case load condition. However, if the UE isdesigned to handle the common load conditions, then the UE may run lowon resources in some scenarios. It may be desirable to effectivelyhandle the scenarios in which the UE runs low on resources.

SUMMARY

Techniques for controlling data transmission in a wireless communicationsystem based on hybrid automatic retransmission (HARQ) are describedherein. The system may support multiple (M) HARQ processes, and eachHARQ process may be used to send one or more packets of data at anygiven moment. In an aspect, a receiver may indicate its currentcapability to receive data in terms of the number of HARQ processes thatit can support. A transmitter may then limit the number of HARQprocesses to use to send data to the receiver based on the number ofHARQ processes supported by the receiver.

In one design of data transmission on the downlink, a UE may determinethe number of HARQ processes (Z) supported by the UE, e.g., based on theamount of resources available at the UE. The UE may send informationindicative of the number of HARQ processes supported by the UE to a NodeB. The UE may thereafter receive data from the Node B on up to Z HARQprocesses. In one design, the UE may receive data for non-guaranteed bitrate (non-GBR) traffic on up to Z HARQ processes and may receive datafor guaranteed bit rate (GBR) traffic on up to M HARQ processesavailable in the system. In another design, the UE may receive data forboth GBR traffic and non-GBR traffic on up to Z HARQ processes. The UEmay also receive data for GBR traffic and non-GBR traffic in othermanners.

The techniques may also be used for data transmission on the uplink.Various aspects and features of the disclosure are described in furtherdetail below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a wireless communication system.

FIG. 2 shows data transmission on the downlink with HARQ.

FIG. 3 shows multiple HARQ processes for synchronous HARQ.

FIG. 4 shows a process for controlling data transmission based on HARQ.

FIG. 5 shows a process for receiving data.

FIG. 6 shows an apparatus for receiving data.

FIG. 7 shows a process for sending data.

FIG. 8 shows an apparatus for sending data.

FIG. 9 shows a block diagram of a Node B and a UE.

DETAILED DESCRIPTION

The techniques described herein may be used for various wirelesscommunication systems such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA and othersystems. The terms “system” and “network” are often usedinterchangeably. A CDMA system may implement a radio technology such asUniversal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA includesWideband CDMA (WCDMA) and other variants of CDMA. cdma2000 coversIS-2000, IS-95 and IS-856 standards. A TDMA system may implement a radiotechnology such as Global System for Mobile Communications (GSM). AnOFDMA system may implement a radio technology such as Evolved UTRA(E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16(WiMAX), IEEE 802.20, Flash-OFDM®, etc. UTRA and E-UTRA are part ofUniversal Mobile Telecommunication System (UMTS). 3GPP Long TermEvolution (LTE) is an upcoming release of UMTS that uses E-UTRA, whichemploys OFDMA on the downlink and SC-FDMA on the uplink. UTRA, E-UTRA,UMTS, LTE and GSM are described in documents from an organization named“3rd Generation Partnership Project” (3 GPP). cdma2000 and UMB aredescribed in documents from an organization named “3rd GenerationPartnership Project 2” (3GPP2). The techniques described herein may beused for the systems and radio technologies mentioned above as well asother systems and radio technologies. For clarity, certain aspects ofthe techniques are described below for LTE.

FIG. 1 shows a wireless communication system 100, which may be an LTEsystem. System 100 may include a number of Node Bs 110 and other networkentities. A Node B may be a station that communicates with the UEs andmay also be referred to as an evolved Node B (eNB), a base station, anaccess point, etc. UEs 120 may be dispersed throughout the system, andeach UE may be stationary or mobile. A UE may also be referred to as amobile station, a terminal, an access terminal, a subscriber unit, astation, etc. A UE may be a cellular phone, a personal digital assistant(PDA), a wireless modem, a wireless communication device, a handhelddevice, a laptop computer, a cordless phone, a wireless local loop (WLL)station, etc. A UE may communicate with a Node B via the downlink anduplink. The downlink (or forward link) refers to the communication linkfrom the Node B to the UE, and the uplink (or reverse link) refers tothe communication link from the UE to the Node B.

The system may support HARQ in order to improve reliability of datatransmission and support rate adaptation for varying channel conditions.For HARQ, a transmitter may send a transmission of a packet and may sendone or more additional transmissions, if needed, until the packet isdecoded correctly by a receiver, or the maximum number of transmissionshas been sent, or some other termination condition is encountered. Apacket may also be referred to as a transport block, a codeword, etc.

FIG. 2 shows an example of data transmission on the downlink with HARQ.The transmission timeline may be partitioned into units of subframes.Each subframe may cover a predetermined time duration, e.g., 1milliseconds (ms) in LTE.

In the example shown in FIG. 2, a Node B may have data to send to a UEand may process a data packet A in accordance with a selected transportformat to obtain data symbols. A transport format may also be referredto as a rate, a packet format, a modulation and coding scheme (MCS),etc. The Node B may send a first transmission of packet A as well ascontrol information to the UE in subframe t. The control information mayindicate the selected transport format, the radio resources used fordata transmission, etc. The UE may receive and process the firsttransmission in accordance with the selected transport format. The UEmay decode packet A in error and may send a negative acknowledgement(NAK) in subframe t+Δ. The Node B may receive the NAK and send a secondtransmission of packet A in subframe t+M. The UE may receive the secondtransmission and process the first and second transmissions inaccordance with the selected transport format. The UE may again decodepacket A in error and may send another NAK in subframe t+M+Δ. The Node Bmay receive the NAK and send a third transmission of packet A insubframe t+2M. The UE may receive the third transmission and process thefirst, second and third transmissions in accordance with the selectedtransport format. The UE may decode packet A correctly and may send anacknowledgement (ACK) in subframe t+2M+Δ. The Node B may receive the ACKand may then process and send another data packet B in similar manner.

The Node B may process and send a packet such that it can be decodedcorrectly with high probability after a target number of transmissions.Each transmission of the packet may be referred to as an HARQtransmission and may include different redundancy information (e.g., adifferent set of data symbols) for the packet. The target number oftransmissions may also be referred to as a target termination for thepacket. A transport format may be selected for the packet based onreceived signal quality such that the target termination can be achievedfor the packet.

The system may support synchronous HARQ and/or asynchronous HARQ. Forsynchronous HARQ, transmissions of a packet may be sent in subframesthat are known a priori by a transmitter and a receiver. Forasynchronous HARQ, transmissions of a packet may be scheduled and sentin any subframes. The techniques described herein may be used for bothsynchronous HARQ and asynchronous HARQ.

FIG. 3 shows a design of synchronous HARQ. M HARQ processes with indicesof 1 through M may be defined for each of the downlink and uplink, whereM may be equal to 4, 6, 8 or some other value. The HARQ processes mayalso be referred to as HARQ interlaces, HARQ instances, etc. Each HARQprocess may include subframes that are spaced apart by M subframes. Forexample, HARQ process m may include subframes m, M+m, 2M+m, etc., wheremε{ 1, . . . , M}. A packet may be sent on one HARQ process, and alltransmissions of the packet may be sent in subframes that are spacedapart by M subframes.

For asynchronous H-ARQ, each HARQ transmission may be scheduled by aNode B and may be sent in any subframe. For a given packet, the amountof radio resources, the specific radio resources, the transport formatand/or other parameters may change for different transmissions of thepacket.

A UE may support guaranteed bit rate (GBR) traffic and non-guaranteedbit rate (non-GBR) traffic. GBR traffic is data that requires a certainguaranteed bit rate in order to achieve satisfactory performance. Someexamples of GBR traffic include data for voice, Voice-over-InternetProtocol (VoIP), video, etc. Mon-GBR traffic is data that does notrequire a guaranteed bit rate and is typically more tolerant to delay.Some examples of non-GBR traffic include data for file downloading, webbrowsing, text messaging, etc. To achieve good user experience,sufficient resources may be allocated at the UE as well as a Node B forGBR traffic. Non-GBR traffic may then be supported with the remainingavailable resources.

The UE may need to handle very high data rates, especially in LTE andother systems supporting high-speed data transmission. The UE may havelimited resources (e.g., limited processing, memory, power, and/or otherresources) for cost effective implementation. The UE may run low onresources during some scenarios, e.g., when an application is launchedwith the UE receiving data at a high rate. In such scenarios, it may bebeneficial for the UE to send signaling to the Node B to request theNode B to reduce data transmission on the downlink in order to alleviateresource requirements at the UE. When the UE resources are back tonormal level, the UE may request the Node B to resume normal datatransmission.

In an aspect, the UE may indicate its current capability to receive datain terms of the number of HARQ processes that it can support. The UE maysupport an overall peak rate of R_(max) when a Node B sends data usingall M HARQ processes available in the system. The UE may support a peakrate of R_(peak)=R_(max)/M for each HARQ process used by the Node B fordata transmission to the UE. The UE may determine the peak rate that itcan support (e.g., for non-GBR traffic) based on the amount of resourcesavailable at the UE (e.g., for non-GBR traffic). The peak rate supportedby the UE may be a function of the available processing resources,memory resources, battery resources, etc.

In one design, the UE may determine the number of HARQ processes that itcan support based on the supported peak rate, as follows:

$\begin{matrix}{{Z = \left\lfloor \frac{R_{supported}}{R_{peak}} \right\rfloor},} & {{Eq}\mspace{14mu}(1)}\end{matrix}$where R_(supported) is the peak rate supported by the UE for all HARQprocesses,

Z is the number of HARQ processes supported by the UE, and

“└ ┘” denotes a floor operator that provides the next lower integervalue.

In general, the UE may determine the number of HARQ processes that itcan support based on any function(s) of resources available at the UE,e.g., for non-GBR traffic or both GBR traffic and non-GBR traffic. Theavailable resources may be mapped directly or indirectly to the numberof supported HARQ processes.

The number of HARQ processes (Z) supported by the UE may be any valuefrom 0 to M, or 0≦Z≦M, where M is the number of HARQ processes availablein the system. For example, Z may be one of nine possible values from 0to 8 for a case in which M=8 HARQ processes are available in the system.Z may then be conveyed with four bits.

The UE may send a data control request to the Node B to ask the Node Bto use no more than Z HARQ processes to send data to the UE. The UE maysend the data control request in various manners. In one design, the UEmay send the data control request via Medium Access Control (MAC), whichmay be responsible for supporting HARQ. In this design, the UE maygenerate a MAC control element containing Z and may send the MAC controlelement to the Node B. In another design, the UE may send the datacontrol request via an upper-layer message, e.g., a Layer 3 (L3)message. In yet another design, the UE may send Z via a channel qualityindicator (CQI) report. One of 2^(B) possible codewords may be sent in aB-bit CQI report. M+1 codewords may be reserved for conveying Z, andremaining codewords may be used to send CQI information. The UE may sendZ in a CQI report by using one of the M+1 codewords reserved forconveying Z. The UE may also send a data control request in othermanners.

FIG. 4 shows a design of a process 400 for controlling data transmissionbased on HARQ. The UE may detect low resources at the UE and may decideto reduce/throttle non-GBR traffic on the downlink (block 412). The UEmay determine the number of HARQ processes (Z₁) supported by the UE fornon-GBR traffic, e.g., based on the resources available at the UE fornon-GBR traffic (block 414). The UE may generate a data control request(e.g., a MAC control element) with the number of supported HARQprocesses (block 416) and may send the data control request to the NodeB (block 418).

The Node B may receive the data control request and may obtain thenumber of HARQ processes (Z₁) supported by the UE (block 422). The NodeB may then limit the number of HARQ processes to use for non-GBR trafficfor the UE to Z₁, e.g., until further notice by the UE (block 424). TheNode B may send data for non-GBR traffic on up to Z₁ HARQ processes tothe UE (block 426).

The UE may detect resources no longer being limited at the UE and maydecide to not reduce non-GBR traffic on the downlink (block 432). The UEmay determine an updated number of HARQ processes (Z₂) supported by theUE for non-GBR traffic (block 434). The UE may generate a data controlrequest with the updated number of supported HARQ processes (block 436)and may send the data control request to the Node B (block 438).

The Node B may receive the data control request and may obtain theupdated number of HARQ processes (Z₂) supported by the UE (block 442).The Node B may then expand the number of HARQ processes to use fornon-GBR traffic for the UE to Z₂, e.g., until further notice by the UE(block 444). The Node B may send data for non-GBR traffic on up to Z₂HARQ processes to the UE (block 446).

In the design shown in FIG. 4, the UE may control the amount of non-GBRtraffic on the downlink by updating the number of HARQ processes (Z)supported by the UE, as needed, and sending the updated Z to the Node B.The Node B may limit the number of HARQ processes to use for non-GBRtraffic for the UE to the latest Z received from the UE.

In another design, the UE may inform the Node B to increase or decreaseZ by a predetermined amount. For example, the UE may send an UP requestto increase the current Z by one or a DOWN request to decrease thecurrent Z by one. The Node B may maintain the current Z for the UE, mayincrease Z whenever an UP request is received from the UE, and maydecrease Z whenever a DOWN request is received.

In one design, a data control request sent by the UE may be “sticky” andmay be valid until another data control request is sent by the UE. Inanother design, a data control request sent by the UE may be valid for apredetermined period of time and may expire automatically after thepredetermined time period. The Node B may apply the data control requestfor the predetermined time period and may revert to a normal setting(e.g., using all M available HARQ processes) when the data controlrequest expires. A data control request may also be applied in othermanners.

In one design, the rate at which the UE can send data control requeststo the Node B may be limited in order to reduce signaling overhead forthe data control requests. In one design, the UE may send a new datacontrol request after waiting at least Q seconds from the prior datacontrol request, where Q may be any suitable value. In another design,the UE may send up to S data control requests per unit of time, where Smay be any suitable value. The unit of time may also cover any suitabletime duration.

In another design, the UE does not send data control requests for thenumber of HARQ processes that it can support. Instead, the Node B mayestimate the number of HARQ processes (Z) that the UE can support basedon NAKs received for HARQ transmissions sent to the UE. The UE may sendmore NAKs when resources are low at the UE. The Node B may keep track ofthe number of NAKs received from the UE and may determine Z based on thereceived NAKs. For example, the Node B may decrease Z by a predeterminedamount if NAKs are received for P1 percent or more of HARQ transmissionssent after the target termination. The Node B may increase Z by apredetermined amount if NAKs are received for P2 percent or less of HARQtransmissions sent after the target termination, where P1>P2. The Node Bmay also update Z in other manners based on NAKs and/or otherinformation.

FIG. 5 shows a design of a process 500 for receiving data in a wirelesscommunication system. Process 500 may be performed by a UE for datatransmission on the downlink (as described below) or by a Node B fordata transmission on the uplink.

The UE may determine the number of HARQ processes supported by the UE(block 512). In one design, the UE may determine the number of supportedHARQ processes (Z) based on the number of HARQ processes (M) availablein the system, an overall peak rate (R_(max)) for all available HARQprocesses, and a peak rate (R_(supported)) supported by the UE. Inanother design, the UE may determine resources used for GBR traffic,determine resources available for non-GBR traffic based on the resourcesused for GBR traffic and the total resources at the UE, and determinethe number of supported HARQ processes based on the resources availablefor non-GBR traffic. The UE may also determine the number of supportedHARQ processes in other manners.

The UE may send information indicative of the number of HARQ processessupported by the UE to a Node B (block 514). In one design, the UE maygenerate a MAC control element carrying the number of supported HARQprocesses and may send the MAC control element to the Node B. In otherdesigns, the UE may send the number of supported HARQ processes usingmessages at other layers or via other mechanisms. The UE may also send achange in the number of supported HARQ processes, e.g., an UP or DOWNrequest.

The UE may receive data from the Node B on up to the number of HARQprocesses supported by the UE (block 516). In one design, the UE mayreceive data for non-GBR traffic on up to the number of supported HARQprocesses. The UE may receive data for GBR traffic on up to all HARQprocesses available in the system. In another design, the UE may receivedata for both GBR traffic and non-GBR traffic on up to the number ofsupported HARQ processes. The UE may also receive data for GBR trafficand non-GBR traffic in other manners.

FIG. 6 shows a design of an apparatus 600 for receiving data in awireless communication system. Apparatus 600 includes a module 612 todetermine the number of HARQ processes supported by a UE, a module 614to send information indicative of the number of HARQ processes supportedby the UE to a Node B, and a module 616 to receive data from the Node Bon up to the number of HARQ processes supported by the UE.

FIG. 7 shows a design of a process 700 for sending data in a wirelesscommunication system. Process 700 may be performed by a Node B for datatransmission on the downlink (as described below) or by a UE for datatransmission on the uplink.

The Node B may receive information indicative of the number of HARQprocesses supported by a UE (block 712). In one design, the Node B mayreceive a MAC control element carrying the number of supported HARQprocesses. The Node B may also receive the number of supported HARQprocesses via other messages at other layers. In one design, the Node Bmay limit the number of HARQ processes to use to send data to the UEbased on the number of supported HARQ processes until informationindicative of an updated number of supported HARQ processes is receivedfrom the UE. In another design, the Node B may limit the number of HARQprocesses to use to send data to the UE for a predetermined time period.

The Node B may send data to the UE on up to the number of HARQ processessupported by the UE (block 714). In one design, the Node B may send datafor non-GBR traffic on up to the number of HARQ processes supported bythe UE and may send data for GBR traffic on up to all HARQ processesavailable in the system. In another design, the Node B may send data forboth GBR traffic and non-GBR on up to the number of HARQ processessupported by the UE. The Node B may also send data for GBR traffic andnon-GBR traffic in other manners.

FIG. 8 shows a design of an apparatus 800 for sending data in a wirelesscommunication system. Apparatus 800 includes a module 812 to receiveinformation indicative of the number of HARQ processes supported by aUE, and a module 814 to send data from a Node B to the UE on up to thenumber of HARQ processes supported by the UE.

The modules in FIGS. 6 and 8 may comprise processors, electronicsdevices, hardware devices, electronics components, logical circuits,memories, software codes, firmware codes, etc., or any combinationthereof.

For clarity, the techniques have been described for controlling datatransmission on the downlink. The techniques may also be used to controldata transmission on the uplink. In one design, the UE may sendinformation indicative of the number of HARQ processes supported by theUE for data transmission on the uplink. The Node B may then schedule theUE for up to the number of HARQ processes supported by the UE on theuplink. The UE may send data, as scheduled, to the Node B. This designmay ensure that radio resources allocated to the UE for datatransmission on the uplink can be utilized by the UE.

The techniques described herein may provide certain advantages. First,the techniques may provide flexibility for UE implementation and maypossibly reduce cost. For example, the UE may share certain resourcesamong different applications to achieve multiplexing gain. Second, theUE may be protected under overload scenarios. Third, the techniques mayprovide an effective means for the UE to cope with a highpeak-to-average data rate ratio without having to over-design the UEwith a large amount of resources. Fourth, the UE may be able to providebetter user experience. For example, the UE may be able to launch anapplication faster by temporarily reducing non-GBR traffic when theapplication is launched. Other advantages may also be obtained with thetechniques described herein.

FIG. 9 shows a block diagram of a design of a Node B 110 and a UE 120,which may be one of the Node Bs and one of the UEs in FIG. 1. In thisdesign, Node B 110 is equipped with T antennas 934 a through 934 t, andUE 120 is equipped with R antennas 952 a through 952 r, where in generalT≧1 and R≧1.

At Node B 110, a transmit processor 920 may receive packets of data froma data source 912 for UE 120. Transmit processor 920 may process (e.g.,encode, interleave, and modulate) the packets for transmission on one ormore HARQ processes, which may be determined based on the number of HARQprocesses supported by UE 120. Transmit processor 920 may also receiveand process control information from a controller/processor 940 andprovide control symbols. A transmit (TX) multiple-input multiple-output(MIMO) processor 930 may perform spatial processing (e.g., precoding) onthe data symbols, the control symbols, and/or pilot symbols, ifapplicable, and may provide T output symbol streams to T modulators(MODs) 932 a through 932 t. Each modulator 932 may process a respectiveoutput symbol stream (e.g., for OFDM, SC-FDM, CDMA, etc.) to obtain anoutput sample stream. Each modulator 932 may further process (e.g.,convert to analog, amplify, filter, and upconvert) the output samplestream to obtain a downlink signal. T downlink signals from modulators932 a through 932 t may be transmitted via T antennas 934 a through 934t, respectively.

At UE 120, antennas 952 a through 952 r may receive the downlink signalsfrom Node B 110 and may provide received signals to demodulators(DEMODs) 954 a through 954 r, respectively. Each demodulator 954 maycondition (e.g., filter, amplify, downconvert, and digitize) arespective received signal to obtain input samples. Each demodulator 954may further process the input samples (e.g., for OFDM, SC-FDM, CDMA,etc.) to obtain received symbols. A MIMO detector 956 may obtainreceived symbols from all R demodulators 954 a through 954 r, performMIMO detection on the received symbols if applicable, and providedetected symbols. A receive processor 958 may process (e.g., demodulate,deinterleave, and decode) the detected symbols, provide decoded packetsfor UE 120 to a data sink 960, and provide decoded control informationto a controller/processor 980.

On the uplink, at UE 120, a transmit processor 964 may receive packetsof data from a data source 962 and control information (e.g.,information indicative of the number of HARQ processes supported by UE120) from controller/processor 980. Transmit processor 964 may processthe packets and control information and provide data symbols and controlsymbols, respectively. The symbols from transmit processor 964 may beprecoded by a TX MIMO processor 966 if applicable, further processed bymodulators 954 a through 954 r, and transmitted to Node B 110. At Node B110, the uplink signals from UE 120 may be received by antennas 934,processed by demodulators 932, detected by a MIMO detector 936 ifapplicable, and further processed by a receive processor 938 to obtainthe decoded packets and control information transmitted by UE 120.

Controllers/processors 940 and 980 may direct the operation at Node B110 and UE 120, respectively. Controller/processor 940 may controltransmission of data for GBR traffic and/or non-GBR traffic to UE 120based on the number of HARQ processes supported by UE 120. Processor 940and/or other processors and modules at Node B 110 may perform or directpart of process 400 in FIG. 4 for the Node B, process 700 in FIG. 7,and/or other processes for the techniques described herein. Processor980 and/or other processors and modules at UE 120 may perform or directpart of process 400 in FIG. 4 for the UE, process 500 in FIG. 5, and/orother processes for the techniques described herein. Memories 942 and982 may store data and program codes for Node B 110 and UE 120,respectively. A scheduler 944 may schedule UEs for data transmission onthe downlink and/or uplink and may provide resource grants for thescheduled UEs.

Those of skill in the art would understand that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or any combination thereof.

Those of skill would further appreciate that the various illustrativelogical blocks, modules, circuits, and algorithm steps described inconnection with the disclosure herein may be implemented as electronichardware, computer software, or combinations of both. To clearlyillustrate this interchangeability of hardware and software, variousillustrative components, blocks, modules, circuits, and steps have beendescribed above generally in terms of their functionality. Whether suchfunctionality is implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem. Skilled artisans may implement the described functionality invarying ways for each particular application, but such implementationdecisions should not be interpreted as causing a departure from thescope of the present disclosure.

The various illustrative logical blocks, modules, and circuits describedin connection with the disclosure herein may be implemented or performedwith a general-purpose processor, a digital signal processor (DSP), anapplication specific integrated circuit (ASIC), a field programmablegate array (FPGA) or other programmable logic device, discrete gate ortransistor logic, discrete hardware components, or any combinationthereof designed to perform the functions described herein. Ageneral-purpose processor may be a microprocessor, but in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

The steps of a method or algorithm described in connection with thedisclosure herein may be embodied directly in hardware, in a softwaremodule executed by a processor, or in a combination of the two. Asoftware module may reside in RAM memory, flash memory, ROM memory,EPROM memory, EEPROM memory, registers, hard disk, a removable disk, aCD-ROM, or any other form of storage medium known in the art. Anexemplary storage medium is coupled to the processor such that theprocessor can read information from, and write information to, thestorage medium. In the alternative, the storage medium may be integralto the processor. The processor and the storage medium may reside in anASIC. The ASIC may reside in a user terminal. In the alternative, theprocessor and the storage medium may reside as discrete components in auser terminal.

In one or more exemplary designs, the functions described may beimplemented in hardware, software, firmware, or any combination thereof.If implemented in software, the functions may be stored on ortransmitted over as one or more instructions or code on acomputer-readable medium. Computer-readable media includes both computerstorage media and communication media including any medium thatfacilitates transfer of a computer program from one place to another. Astorage media may be any available media that can be accessed by ageneral purpose or special purpose computer. By way of example, and notlimitation, such computer-readable media can comprise RAM, ROM, EEPROM,CD-ROM or other optical disk storage, magnetic disk storage or othermagnetic storage devices, or any other medium that can be used to carryor store desired program code means in the form of instructions or datastructures and that can be accessed by a general-purpose orspecial-purpose computer, or a general-purpose or special-purposeprocessor. Also, any connection is properly termed a computer-readablemedium. For example, if the software is transmitted from a website,server, or other remote source using a coaxial cable, fiber optic cable,twisted pair, digital subscriber line (DSL), or wireless technologiessuch as infrared, radio, and microwave, then the coaxial cable, fiberoptic cable, twisted pair, DSL, or wireless technologies such asinfrared, radio, and microwave are included in the definition of medium.Disk and disc, as used herein, includes compact disc (CD), laser disc,optical disc, digital versatile disc (DVD), floppy disk and blu-ray discwhere disks usually reproduce data magnetically, while discs reproducedata optically with lasers. Combinations of the above should also beincluded within the scope of computer-readable media.

The previous description of the disclosure is provided to enable anyperson skilled in the art to make or use the disclosure. Variousmodifications to the disclosure will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other variations without departing from the spirit or scopeof the disclosure. Thus, the disclosure is not intended to be limited tothe examples and designs described herein but is to be accorded thewidest scope consistent with the principles and novel features disclosedherein.

What is claimed is:
 1. A method of receiving data in a wirelesscommunication system, comprising: determining a number of hybridautomatic retransmission (HARQ) processes supported by a user equipment(UE); sending information indicative of the number of HARQ processessupported by the UE to a base station; and receiving data from the basestation through one or more HARQ processes, wherein the number of theone or more HARQ processes does not exceed the number of HARQ processessupported by the UE.
 2. The method of claim 1, wherein determining thenumber of HARQ processes supported by the UE comprises determining thenumber of HARQ processes supported by the UE based on total number ofHARQ processes available in the system, an overall peak rate for allavailable HARQ processes, and a peak rate supported by the UE.
 3. Themethod of claim 1, wherein determining the number of HARQ processessupported by the UE comprises determining resources available at the UEfor non-guaranteed bit rate (non-GBR) traffic, and determining thenumber of HARQ processes supported by the UE based on the resourcesavailable for non-GBR traffic.
 4. The method of claim 3, whereindetermining the number of HARQ processes supported by the UE furthercomprises determining resources used for guaranteed bit rate (GBR)traffic, and determining the resources available for non-GBR trafficbased on the resources used for GBR traffic and total resources at theUE.
 5. The method of claim 1, wherein sending information indicative ofthe number of HARQ processes supported by the UE comprises generating aMedium Access Control (MAC) control element carrying the number of HARQprocesses supported by the UE, and sending the MAC control element tothe base station.
 6. The method of claim 1, wherein receiving the datacomprises receiving data for non-guaranteed bit rate (non-GBR) trafficfrom the base station through the one or more HARQ processes.
 7. Themethod of claim 6, further comprising receiving data for guaranteed bitrate (GBR) traffic from the base station through one or more HARQprocesses available in the system.
 8. The method of claim 1, whereinreceiving the data comprises receiving data for both guaranteed bit rate(GBR) traffic and non-guaranteed bit rate (non-GBR) traffic through theone or more HARQ processes.
 9. An apparatus for wireless communication,comprising: a wireless transceiver; and at least one processor coupledto the wireless transceiver and configured to determine a number ofhybrid automatic retransmission (HARQ) processes supported by a userequipment (UE), to send information indicative of the number of HARQprocesses supported by the UE to a base station through the wirelesstransceiver, and to receive data from the base station through one ormore HARQ processes, wherein the number of the one or more HARQprocesses does not exceed the number of HARQ processes supported by theUE.
 10. The apparatus of claim 9, wherein the at least one processor isconfigured to determine resources available at the UE for non-guaranteedbit rate (non-GBR) traffic, and to determine the number of HARQprocesses supported by the UE based on the resources available fornon-GBR traffic.
 11. The apparatus of claim 9, wherein the at least oneprocessor is configured to generate a Medium Access Control (MAC)control element carrying the number of HARQ processes supported by theUE, and to send the MAC control element to the base station.
 12. Theapparatus of claim 9, wherein the at least one processor is configuredto receive data for non-guaranteed bit rate (non-GBR) traffic from thebase station through the one or more HARQ processes.
 13. The apparatusof claim 9, wherein the at least one processor is configured to receivedata for both guaranteed bit rate (GBR) traffic and non-guaranteed bitrate (non-GBR) traffic through the one or more HARQ processes.
 14. Anapparatus for wireless communication, comprising: processing means fordetermining a number of hybrid automatic retransmission (HARQ) processessupported by a user equipment (UE); and a wireless transceivercommunicatively coupled to the processing means, the wirelesstransceiver including: means for sending information indicative of thenumber of HARQ processes supported by the UE to a base station; andmeans for receiving data from the base station through one or more HARQprocesses, wherein the number of the one or more HARQ processes does notexceed the number of HARQ processes supported by the UE.
 15. Theapparatus of claim 14, wherein the means for determining the number ofHARQ processes supported by the UE comprises means for determiningresources available at the UE for non-guaranteed bit rate (non-GBR)traffic, and means for determining the number of HARQ processessupported by the UE based on the resources available for non-GBRtraffic.
 16. The apparatus of claim 14, wherein the means for sendinginformation indicative of the number of HARQ processes supported by theUE comprises means for generating a Medium Access Control (MAC) controlelement carrying the number of HARQ processes supported by the UE, andmeans for sending the MAC control element to the base station.
 17. Theapparatus of claim 14, wherein the means for receiving the datacomprises means for receiving data for non-guaranteed bit rate (non-GBR)traffic from the base station through the one or more HARQ processes.18. The apparatus of claim 14, wherein the means for receiving the datacomprises means for receiving data for both guaranteed bit rate (GBR)traffic and non-guaranteed bit rate (non-GBR) traffic through the one ormore HARQ processes.
 19. A computer program product, comprising: anon-transitory computer-readable medium comprising: code stored on themedium for causing at least one computer to determine a number of hybridautomatic retransmission (HARQ) processes supported by a user equipment(UE), code stored on the medium for causing the at least one computer tosend information indicative of the number of HARQ processes supported bythe UE to a base station, and code stored on the medium for causing theat least one computer to receive data from the base station through oneor more HARQ processes, wherein the number of the one or more HARQprocesses does not exceed the number of HARQ processes supported by theUE.
 20. A method of sending data in a wireless communication system,comprising: receiving information indicative of a number of hybridautomatic retransmission (HARQ) processes supported by a user equipment(UE); and sending data from a base station to the UE through one or moreHARQ processes, wherein the number of the one or more HARQ processesdoes not exceed the number of HARQ processes supported by the UE. 21.The method of claim 20, further comprising limiting the number of theone or more HARQ processes used to send the data to the UE to the numberof HARQ processes supported by the UE until information indicative of anupdated number of HARQ processes supported by the UE is received fromthe UE.
 22. The method of claim 20, further comprising limiting thenumber of the one or more HARQ processes used to send the data to the UEto the number of HARQ processes supported by the UE for a predeterminedperiod of time.
 23. The method of claim 20, wherein receiving theinformation indicative of the number of HARQ processes supported by theUE comprises receiving a Medium Access Control (MAC) control elementcarrying the number of HARQ processes supported by the UE.
 24. Themethod of claim 20, wherein sending the data comprises sending data fornon-guaranteed bit rate (non-GBR) traffic from the base station to thethrough the one or more HARQ processes.
 25. The method of claim 24,further comprising sending data for guaranteed bit rate (GBR) trafficfrom the base station to the UE through one or more HARQ processesavailable in the system.
 26. The method of claim 20, wherein sending thedata comprises sending data for both guaranteed bit rate (GBR) trafficand non-guaranteed bit rate (non-GBR) traffic from the base station tothe UE through the one or more HARQ processes.
 27. An apparatus forwireless communication, comprising: a wireless transceiver; and at leastone processor communicatively coupled to the wireless transceiver andconfigured to receive information indicative of a number of hybridautomatic retransmission (HARQ) processes supported by a user equipment(UE), and to send data from a base station to the UE through one or moreHARQ processes, wherein the number of the one or more HARQ processesdoes not exceed the number of HARQ processes supported by the UE. 28.The apparatus of claim 27, wherein the at least one processor isconfigured to receive a Medium Access Control (MAC) control elementcarrying the number of HARQ processes supported by the UE.
 29. Theapparatus of claim 27, wherein the at least one processor is configuredto send data for non-guaranteed bit rate (non-GBR) traffic from the basestation to the UE through the one or more HARQ processes.
 30. Theapparatus of claim 27, wherein the at least one processor is configuredto send data for both guaranteed bit rate (GBR) traffic andnon-guaranteed bit rate (non-GBR) traffic from the base station to theUE through the one or more HARQ processes.
 31. A method of exchangingdata in a wireless communication system, comprising: determining anumber of hybrid automatic retransmission (HARQ) processes supported bya user equipment (UE); and exchanging data through one or more HARQprocesses, wherein the number of the one or more HARQ processes does notexceed the number of HARQ processes supported by the UE.
 32. The methodof claim 31, wherein exchanging the data comprises receiving data from abase station through the one or more HARQ processes.
 33. The method ofclaim 31, wherein exchanging the data comprises sending data from the UEto a base station through the one or more HARQ processes.
 34. The methodof claim 31, wherein determining the number of HARQ processes supportedby the UE comprises determining the number of HARQ processes supportedby the UE based on resources available at the UE for non-guaranteed bitrate (non-GBR) traffic.
 35. The method of claim 31, wherein determiningthe number of HARQ processes supported by the UE comprises determiningthe number of HARQ processes supported by the UE based on negativeacknowledgements (NAKs) received from the UE for prior transmissions ofdata sent to the UE.
 36. An apparatus for wireless communication,comprising: means for transmitting and receiving data or controlinformation wirelessly; means for determining a number of hybridautomatic retransmission (HARQ) processes supported by a user equipment(UE); and means for exchanging data through one or more HARQ processes,wherein the number of the one or more HARQ processes does not exceed thenumber of HARQ processes supported by the UE.
 37. The apparatus of claim36, wherein the means for exchanging the data receives data from a basestation through the one or more HARQ processes.
 38. The apparatus ofclaim 36, wherein the means for exchanging the data sends data from theUE to a base station through the one or more HARQ processes.
 39. Theapparatus of claim 36, wherein the means for determining the number ofHARQ processes supported by the UE determines the number of HARQprocesses supported by the UE based on resources available at the UE fornon-guaranteed bit rate (non-GBR) traffic.
 40. The apparatus of claim36, wherein the means for determining the number of HARQ processessupported by the UE determines the number of HARQ processes supported bythe UE based on negative acknowledgements (NAKs) received from the UEfor prior transmissions of data sent to the UE.
 41. An apparatus forwireless communication, comprising: a processing system configured to:determine a number of hybrid automatic retransmission (HARQ) processessupported by a user equipment (UE); and exchanging data through one ormore HARQ processes, wherein the number of the one or more HARQprocesses does not exceed the number of HARQ processes supported by theUE.
 42. The apparatus of claim 41, wherein exchanging the data comprisesreceiving data from a base station through the one or more HARQprocesses.
 43. The apparatus of claim 41, wherein exchanging the datacomprises sending data from the UE to a base station through the one ormore HARQ processes.
 44. The apparatus of claim 41, wherein determiningthe number of HARQ processes supported by the UE comprises determiningthe number of HARQ processes supported by the UE based on resourcesavailable at the UE for non-guaranteed bit rate (non-GBR) traffic. 45.The apparatus of claim 41, wherein determining the number of HARQprocesses supported by the UE comprises determining the number of HARQprocesses supported by the UE based on negative acknowledgements (NAKs)received from the UE for prior transmissions of data sent to the UE. 46.A computer program product, comprising: a non-transitorycomputer-readable medium comprising code for: determining number ofhybrid automatic retransmission (HARQ) processes supported by a userequipment (UE); and exchanging data through one or more HARQ processes,wherein the number of the one or more HARQ processes does not exceed thenumber of HARQ processes supported by the UE.
 47. An apparatus forwireless communication, comprising: means for transmitting and receivingdata or control information wirelessly; means for receiving informationindicative of a number of hybrid automatic retransmission (HARQ)processes supported by a user equipment (UE); and means for sending datafrom a base station to the UE through one or more HARQ processes,wherein the number of the one or more HARQ processes does not exceed thenumber of HARQ processes supported by the UE.
 48. The apparatus of claim47, wherein the means for sending the data limits the number of the oneor more HARQ processes used to send the data to the number of HARQprocesses supported by the UE until information indicative of an updatednumber of HARQ processes supported by the UE is received from the UE.49. The apparatus of claim 47, wherein the means for sending the datalimits the number of the one or more HARQ processes to the number ofHARQ processes supported by the UE for a predetermined period of time.50. The apparatus of claim 47, wherein the means for receiving theinformation indicative of the number of HARQ processes supported by theUE is configured to receive a Medium Access Control (MAC) controlelement carrying the number of HARQ processes supported by the UE. 51.The apparatus of claim 47, wherein the means for sending the data sendsdata for non-guaranteed bit rate (non-GBR) traffic from the base stationto the UE through the one or more HARQ processes.
 52. The apparatus ofclaim 51, wherein the means for sending the data sends data forguaranteed bit rate (GBR) traffic from the base station to the UEthrough one or more HARQ processes available in the system.
 53. Theapparatus of claim 47, wherein the means for sending the data sends datafor both guaranteed bit rate (GBR) traffic and non-guaranteed bit rate(non-GBR) traffic from the base station to the UE through the one ormore HARQ processes.
 54. A computer program product, comprising: anon-transitory computer-readable medium comprising code for: receivinginformation indicative of a number of hybrid automatic retransmission(HARQ) processes supported by a user equipment (UE); and sending datafrom a base station to the UE through one or more HARQ processes,wherein the number of the one or more HARQ processes does not exceed thenumber of HARQ processes supported by the UE.